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Biomedical subjects

C Ribot

Publications and source records attributed to C Ribot.

At least 91 records · Page 5Linked to original sources
PubMed1992

[Comparative effects of sodium fluoride and hormonal replacement therapy on bone metabolism in osteoporotic women with high fracture risk. Results of monitoring for 2 years].

Thirty seven postmenopausal women aged under 65 with densitometric osteoporosis defined by a bone density value below the 80th percentile of the osteoporotic population but without identifiable crush fractures, were treated and monitored for two years using clinical, laboratory and densitometric parameters. Sixteen of them were given hormonal replacement therapy combining percutaneous or transdermal 17 beta estradiol with a progestogen and the other 21 sodium fluoride at the dose of 50 mg/d combined with calcium and vitamin D. There was a significant increase in vertebral bone density in both groups: 6.3 +/- 0.9 per cent for hormone treatment and 7.1 +/- 1.5% for fluoride after 2 years, while it fell in a control group. The increase was linear with fluoride, while 2/3 of the gain was acquired by the end of the first year of hormonal therapy. Nine of the 16 patients on hormonal therapy and 9 of the 21 taking fluoride showed a significant vertebral gain at 2 years (greater than or equal to 0.043 g/cm2). There was no parameter which enabled the identification of "responders" before treatment. There was no difference in changes in femoral bone density between patients treated with fluoride and controls. From a laboratory standpoint, hormonal therapy caused a significant fall at 12 months in the urinary calcium/urinary creatinine ratio, and a non-significant fall in osteocalcin at 2 years. With fluoride, there was a marked rise in osteocalcin and a more moderate rise in alkaline phosphatase, reflecting stimulation of bone formation without any variation in resorption. In conclusion, this study shows the ability of both these types of treatment of increasing, by different mechanisms, the vertebral bone density of osteoporotic women. However, it does not indicate the extent to which this gain in bone density might have a positive influence on fracture risk.

Age Factors↗
PubMed1992

[Lower limb arteriopathy and male osteoporosis].

There are close links between bone metabolism and bone circulation. Osteoblasts are derived from the walls of the venous sinuses. As shown by Burkardt, osteoporosis is accompanied by a decrease in the number of intra-osseous capillaries, and intra-osseous arterioles may be the site of arteriosclerosis lesions. In order to determine the existence of a possible link between arteriosclerosis and male osteoporosis, the etiology of which is often poorly defined, the authors studied phosphorus-calcium balance, X-rays of the spine, and bone density of the spine and the femoral neck in 17 male arterial disease sufferers with a mean age of 61 and at Leriche stage 2, 3 or 4. These 17 patients were compared with 15 age-paired controls. Wedge fractures, absent in the control group, were seen in 9 of the 17 patients. Bone mineral content in the femoral neck was significantly reduced in the arterial disease group.

Arteriosclerosis↗
PubMed1991

Precision and sensitivity of dual-energy x-ray absorptiometry in spinal osteoporosis.

This study evaluated the performance of dual-energy x-ray absorptiometry (DEXA) with regard to (1) the correlation with dual-photon absorptiometry (DPA), (2) the ability to discriminate between normal and osteoporotic patients, and (3) long-term reproducibility. The bone mineral density (BMD) of the spine in 112 subjects, both normal and osteoporotic, was measured with DPA and DEXA (Lunar Corporation, Madison, Wisconsin) of the spine. The femur BMD of 22 cases was also measured with both machines. The results for the two techniques were highly correlated (r greater than 0.9, SEM = 0.02 to 0.04 g/cm2). BMD was measured using DEXA in 80 women (mean age = 61 years) with established spinal osteoporosis and 110 normal age-matched controls. The osteoporotic patients had significantly reduced spine and femur BMDs compared to the controls: -23% for L2-4 BMD (Z score = 2.6) and -13 to -20% for femur BMD (Z score = 1.1-1.3). L2-4 BMD had the best discriminative value, with an area under the ROC curve of 94%; the Ward's triangle BMD had an area of 84%. The precision error in vitro in a phantom over a 1-year period was 0.7%. The measured precision in vivo with young adults was approximately 1% (SD = 0.012 g/cm2) for L2-4 BMD and 1.7-2.3% (SD = 0.015-0.022 g/cm2) for femur over the 1 year period. The reproducibility was not as good for osteoporotic patients (SD = 0.017 g/cm2).

Absorptiometry, Photon↗
PubMed1991

Fluoride therapy in postmenopausal osteopenic women: effect on vertebral and femoral bone density and prediction of bone response.

Fifty-two postmenopausal women (mean age 60 +/- 5 years) with low BMD (less than -2SD of young adult values) but who had not experienced previous crush fracture were treated with 50 mg of sodium fluoride (NaF), 1 g of calcium and 400 IU of vitamin D2 per day for 2 years. Repeated vertebral and femoral BMD measurements were made and compared with those of a control group consisting of 16 untreated women. Serum alkaline phosphatase and osteocalcin, blood and urinary fluoride levels were measured regularly to determine their predictive value on bone response. 18 of 52 (35%) of the treated patients experienced side effects (29% gastric, 4% lower extremity pain syndrome) but only in 6 cases (12%) was it necessary to discontinue treatment. In neither of the two groups was any fracture recorded (vertebral or otherwise). Among the 43 women who were treated for at least 2 years, 21 (49%) were considered to have responded (i.e., with an increase of vertebral BMD greater than 0.043 g/cm2). There was a mean linear increase in BMD in this group of 0.0041 g/cm2 per month (i.e., 5.5% per year). On the other hand in the non-responder group and in the control group, vertebral BMD either remained stable or decreased. However no difference was detected between the two groups (treated and controls) at the femoral site after 2 years; both groups showed a significant decrease in BMD. The responders had a lower initial osteocalcin level and treatment led to a relatively greater increase in osteocalcin.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1991

[Transitory bone loss during substitution treatment for hypothyroidism. Results of a two year prospective study].

The authors report the results of a prospective study designed to assess changes in vertebral and femoral bone density during the first two years of replacement therapy in 10 patients with hypothyroidism (4 men, 6 women). During the first year, bone density measured by dual photon absorptiometry fell significantly in the lumbar vertebrae (-5.4%), neck of the femur (-7%) and the trochanteric region (-7.3%). This bone loss was accompanied by an early increase in serum osteocalcin levels, urinary calcium/urinary creatinine ratio and in Sex Hormone Binding Globulin. During the second year, there was complete recovery of values of vertebral and trochanteric bone density, while density of the neck of the femur remained significantly lower than initial values. None of the patients showed any evidence of overdose during the period of monitoring of clinical and laboratory (free T4, total and free T3, ultra-sensitive TSH) parameters. This transitory bone loss could be indicative of a state of tissue hyperthyroidism and/or "hypersensitivity" of hypothyroid bone to the action of thyroid hormones. Its influence on the subsequent risk of fracture remains unclear. In the current state of knowledge, measurement of vertebral and femoral bone density appears to be indicated in patients given long term treatment which suppresses TSH, or requiring replacement therapy for severe hypothyroidism. Any demineralisation prior to treatment could justify the temporary prescription of an antiosteoclastic agent.

Adult↗
PubMed1991

[Risk factors of vertebral osteoporosis. Results of a study of 2279 women referred to a menopause clinic].

The principal clinical risk factors of osteoporosis were correlated with vertebral bone density measured by biphoton absorptiometry in 2,279 women referred to a menopause clinic. Age, age at puberty, the menopause and how long ago it had occurred, smoking and past history of osteoporosis were negatively and independently correlated with bone density. Early onset of the menopause significantly increased the risk of a low bone density as compared with a natural or surgical menopause occurring after the age of 45. In contrast, estrogen replacement therapy and excess weight decreased this risk after the menopause. Osteoarthrosis and 25 (OH) vit. D3 levels were positively correlated with bone density. These variables taken together in a multiple linear regression model were able to explain only 25 per cent of the variations in bone density between individuals, suggesting the predominant role of other factors not taken into account in our study, notably of a genetic and environmental nature. Before the menopause, none of the factors studied enabled prediction of the risk defined by a low bone density. Among women with one or more clinical risk factors correlated with bone density, 29 per cent in fact had low bone density, as compared with 20 per cent in the absence of such factors. In contrast, 54 per cent of women with a low bone density had no risk factor. The results of this study show that the exception of secondary causes of osteoporosis, the majority of so-called "risk" factors which can be assessed by history have only a minimal influence on bone density.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorptiometry, Photon↗
PubMed1990

Bone mineral density and thyroid hormone therapy.

The purpose of this study was to evaluate prospectively the evolution of femoral and vertebral bone mineral density (BMD) in hypothyroid subjects treated with replacement doses (mean +/- SD dose of L-thyroxine = 135 +/- 32 micrograms/day) as compared to an untreated group. Vertebral bone density was also measured in other patients who had been treated for at least 2 years with either suppressive (mean dose = 154 +/- 36 micrograms/day, n = 28) or replacement doses (mean dose = 104 +/- 52 micrograms/day, n = 21) according to the thyrotrophin response (TSH) to the thyrotrophin releasing hormone (TRH) administration. In primary hypothyroid patients, a mean decrease of 5.4% (P less than 0.01) for vertebral BMD, 7.3% (P less than 0.01) for trochanter and 7% (P less than 0.001) for femoral neck was observed after 1 year of treatment. This loss was unrelated either to age or to menopausal status (ANOVA). A clinical and hormonal state of euthyroidism was reached since the 3rd month of treatment. Fasting urinary calcium/creatinine excretion was increased significantly (P less than 0.05) at the 3rd month, and plasma osteocalcin (OC) increased significantly from the 3rd month onwards (P less than 0.05) up to the 12th month (P less than 0.025). In the cross-sectional study, vertebral BMD was not significantly different from age-matched normal values in patients receiving either substitutive or suppressive doses of LT4. These results suggest that in the case of primary hypothyroidism even appropriate thyroid replacement therapy could lead during the first year of treatment to a significant reduction in vertebral and femoral BMD. However, the fact that an increased fracture rate has not been documented in long-term treated patients, and the results of our cross-sectional study, suggest that this bone mass reduction could be transient and reversible due to new bone formation at the end of the resorptive sequence.

Adult↗
PubMed1990

[Performance of X-ray absorptiometry in post-menopausal vertebral osteoporosis. Discriminant value of vertebral and femoral measurements, fracture threshold, reproducibility].

The aim of this study was to assess the performance of a new bone densitometry technique, X-ray absorptiometry, in vertebral osteoporosis with fracture(s). Vertebral and femoral (neck, Ward's triangle and trochanter) bone density was measured in 60 women with at least one vertebral compression fracture of osteoporotic origin (mean age: 61), 100 controls of the same age and in 40 young adults (mean age: 30). Osteoporosis patients had significantly (p less than 0.0005) low bone density values in comparison with the young adults: -40 to -50% (T-score -1.9 to -2.3) for the femur and with control subjects of the same age: -20 to -30% (Z-score -2.2 to -2.6) for the spine; -10 to -20 (Z-score -1.1 to -1.3) for the femur. Measurements using the spine and Ward's triangle had the best discriminant values assessed by the ROC (Receiver Operating Characteristics) technique (areas under the curve: 95% and 84% respectively). The fracture threshold was fixed at a vertebral bone density of 0.78 g/cm2, this value giving the best compromise between sensitivity (83%) and specificity (95%) with 91% of subjects appropriately classified. Reproducibility was assessed in the short term in 9 osteoporosis patients. The mean standard deviation of measurements was 0.017 g/cm2 (coefficient of variation: 2.6%) as compared with 0.010 g/cm2 (coefficient of variation: 0.8%) in the young adult. These results emphasise the true advance represented by X-ray absorptiometry in the area of bone densitometry, notably in the assessment and monitoring of demineralisation disorders.

Absorptiometry, Photon↗
PubMed1989

Femoral bone density in young male adults with stress fractures.

Femoral bone mineral density (BMD) was measured by dualphoton absorptiometry in 41 young military recruits who had one or several stress fractures, during their physical training program. These fractures involved the following locations: Femur (neck: n = 10, diaphysis: n = 2), calcaneus (n = 10), tibia (n = 8), fibula (n = 3), metatarsus (n = 8). The stress fracture group generally had a lower bone density than that of a control group, consisting of 48 young military recruits matched for age, height and weight. However, the BMD was significantly lower (-10%) in patients with femoral and calcaneal locations, but it did not differ for other locations. To determine the possible effect of this intense physical activity on bone mineral mass, bone mass was measured again in 35 subjects from the control group at the end of their training. The BMD remained stable or increased in 28 subjects, but decreased significantly (greater than 2%) in 7 subjects, demonstrating the individual variability in the adaptation of bone to this stress. Our results suggest that lowered bone mass could be a factor that encourages the development of stress fractures (femoral and calcaneal) in young subjects submitted to intense physical activity to which they are not accustomed.

Adolescent↗
PubMed1989

Preventive effects of transdermal administration of 17 beta-estradiol on postmenopausal bone loss: a 2-year prospective study.

A 2-year prospective study was conducted on 44 early postmenopausal women to assess the effect of transdermal estradiol (TTS-E2) on vertebral bone mass. Twenty treated women and 24 untreated were studied. Treatment consisted of TTS-E2 (0.05 mg/day, 3 weeks a month) and an oral gestagen (10 days per month). At 24 months, bone mineral density, measured by Dual Photon Absorptiometry (DPA), decreased significantly in untreated women (-4.3%) (p less than 0.001), while treated women had a net gain of +5.4% (p less than 0.001). Bone turnover parameters (serum osteocalcin, urinary calcium/creatinine ratio) were significantly (p less than 0.05) reduced from the 2nd month of treatment onwards. Serum estradiol levels were sustained during the treatment and were in the range of an early follicular phase (approximately 45 pg/ml). These findings suggest that low doses of transdermal estradiol sufficient to relieve menopausal symptoms, and which, due to the association with progestogen, result in regular withdrawal bleeding, are effective in preventing postmenopausal bone loss.

Administration, Cutaneous↗
PubMed1989

[What to expect from the measurement of bone mass?].

The development of non-invasive methods to measure the mineral content of bones, represent a major advance for the diagnosis and the follow-up of these demineralizing diseases. The use of these techniques, including biphotonic absorptiometry, is based on a close relationship between mineral content and bone resistance. However we are lacking prospective data permitting to evaluate the value of bone density in terms of subsequent risk of fracture. The presence of interpopulation and inter apparatus variations, the various ways of expressing the results, make it necessary, prior to any study, to specify reference value that are appropriate to each center. Also, the knowledge of short and long-term coefficients of variation, in normal and osteoporotic patients, is absolutely necessary to an accurate evaluation of the variations with time. Measurement of the mineral content in bones enables to consider the early diagnosis of osteoporosis before the fracture stage, and screening of risk patients. Because of their therapeutic implications, it would be desirable that a consensus be established on a precise definition of these densitometric notions.

Bone and Bones↗
PubMed1988

Sensitivity of dual-photon absorptiometry in spinal osteoporosis.

Lumbar spine bone mass and density were measured with Dual photon absorptiometry (DPA) in 60 patients with crush fractures and 60 age-matched normal women. Short-term reproducibility of bone mineral density (BMD) was 1.3% in normal women and 2.5% in osteoporotic women; long-term reproducibility in normal women was 2.2%. The reproducibility of bone mineral content (BMC) seemed to be poorer than that of BMD. In this study, aortic calcifications had no effect on BMD, and one or two crush fractures in the L2-L4 region increased BMD by an average of 3% (0-10%). Lumbar spine DPA provided high sensitivity for these younger crush fracture osteoporotic patients (x = 65 years). The sensitivity at 95% specificity was 74% for BMD and 73% for BMC. This sensitivity is substantially better than that reported for DPA instruments giving higher variances or for quantitative computed tomography.

Aged↗